Just 15 minutes of exercise lowers a child's chances of being obese by almost 50 per cent

Everyone knows children are getting fatter and that both a poor diet and a lack of exercise are to blame. But, what researchers have been unable to discover until now, is exactly how major a role activity plays in the battle to keep obesity at bay.

A new report published in the journal PLoS Medicine, offers new hope for parents concerned about the growing obesity epidemic. It suggests that making even small increases to your daily exercise routine, such as walking your child to school each day instead of taking the car, could have dramatic long-term results.

Using the latest cutting-edge techniques, researchers from Bristol University's Children of the 90s project discovered that doing 15 minutes a day of moderate exercise lowered a child’s chances of being obese by almost 50 per cent.  As long as the activity was at least of the level of a brisk walk - enough to make your child a little out a breath - it seemed to be of benefit.

What makes the results particularly startling is both the large number of UK children studied and the use of high-tech equipment, providing the most accurate measures of both fat and activity levels ever achieved for a study of this type.

Researchers monitored 5,500 12-year-olds from the Children of the 90s research project (also known as ALSPAC, the Avon Longitudinal Study of Parents and Children) based at the University of Bristol,  measuring their activity levels for 10 hours a day.

Each child wore a special ‘Actigraph activity monitor’, which sits on a belt around the waist and records every move they made. Most wore the movement-sensitive monitor for a week but all used the Actigraph for at least three days.

They also had their body fat measured using an X-ray emission scanner, which differentiates both muscle and fat deposits in the body. This is far more precise than the usual BMI (Body Mass Index) system often used to estimate fat levels.

Heading up the research is Professor Chris Riddoch from Bath University together with Children of the 90s’ co-director Professor Andy Ness and his team at Bristol.

Professor Riddoch explained the significance of their results, "This study provides some of the first robust evidence on the link between physical activity and obesity in children.

"We know that diet is important - but what this research tells us is that we mustn’t forget about activity. It’s been really surprising to us how even small amounts of exercise appear to have dramatic results."

Professor Ness added, "The association between physical activity and obesity we observed was strong. These associations suggest that modest increases in physical activity could lead to important reductions in childhood obesity."

He also stressed that doing 15 minutes of moderate exercise a day should be regarded as a starting point, but one most people would find able to fit into their life-style.

The team will now be taking their research further - looking to see if specific patterns of exercise can help achieve even better results.